Image sensors of this type have, as the central component, a two-dimensional charge-coupled semiconductor component formed in rows or as a matrix and serving for processing electrical and optical signals. The image sensor records the information in the form of data by detecting light radiation (object light) and generating electrical charges and forwards the latter. For this purpose, it has an array of up to a few million pixels (gate electrodes) that convert the received light into electrical signals. Moreover, an analogue/digital storage device converts said electrical signals into digital signals which are directly available and are stored in data storage units.
Image sensors of this type are also used in optical, in particular holographic, storage systems in which information is stored in the form of data pages in a two-dimensional data area or a three-dimensional data volume of a storage medium (disc, card), in order to retrieve and acquire stored data by exposing the storage medium using a laser beam bundle.
In general, laser beam bundles have an inhomogeneous, in particular Gaussian, intensity distribution associated with an inhomogeneous exposure of the data page impinged upon on the storage medium, an inhomogeneous contrast resulting from this exposure on said data page, and consequently also an inhomogeneous intensity distribution on the image sensor activated during an exposure. This is regarded as disadvantageous since the read-out of the information contained in the data page is effected simultaneously by the image sensor and takes longer in the lower-contrast zones, which is associated with an increase in the exposure time.